docs: Rephrase the video 'none' type to clarify the reasoning

Signed-off-by: Erik Skultety <eskultet@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
This commit is contained in:
Erik Skultety 2020-09-08 11:55:27 +02:00
parent 34e203ec2d
commit 84f911d3ba

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@ -5784,13 +5784,16 @@ A video device.
value "vga", "cirrus", "vmvga", "xen", "vbox", "qxl" ( :since:`since 0.8.6`
), "virtio" ( :since:`since 1.3.0` ), "gop" ( :since:`since 3.2.0` ), "bochs"
( :since:`since 5.6.0` ), "ramfb" ( :since:`since 5.9.0` ), or "none" (
:since:`since 4.6.0` , depending on the hypervisor features available. The
purpose of the type ``none`` is to instruct libvirt not to add a default
video device in the guest (see the paragraph above). This legacy behaviour
can be inconvenient in cases where GPU mediated devices are meant to be the
only rendering device within a guest and so specifying another ``video``
device along with type ``none``. Refer to Host device assignment to see how
to add a mediated device into a guest.
:since:`since 4.6.0` ), depending on the hypervisor features available.
Note: The purpose of the type ``none`` is to instruct libvirt not to add a
default video device in the guest (see the ``video`` element description
above), since such behaviour is inconvenient in cases where GPU mediated
devices are meant to be the only rendering device within a guest. If this
is your use case specify a ``none`` type ``video`` device in the XML to stop
the default behaviour. Refer to `Host device assignment
<#host-device-assignment>`__ to see how to add a mediated device into a
guest.
You can provide the amount of video memory in kibibytes (blocks of 1024
bytes) using ``vram``. This is supported only for guest type of "vz", "qemu",